An Iranian convert to Christianity imprisoned for his faith since August has reportedly fallen seriously ill after going on hunger strike, but has been refused medical treatment.

According to persecution watchdog World Watch Monitor, Amin Afshar Naderi went on hunger strike on February 5 along with his fellow detainee Hadi Asgari. Both men were among a group of five Christians arrested while picnicking in the Alborz Mountains north-east of Tehran last summer. While the other three Christians were released last year, Naderi and Asgari were unable to raise the amount of money needed for their release.

The Christians were arrested for "illegal evangelism," but no charges have been brought against the five men, despite months of interrogation and imprisonment, according to WWM

Naderi and Asgari are not the first Christians to go on hunger strike in an Iranian prison; Maryam Naghash Zargaran, an Iranian Christian woman sentenced to four-years in sentence for practicing her Christian faith, went on an indefinite hunger strike until her demand for early conditional release for medical treatment was met.

The 36-year-old woman, who was arrested for her work at an orphanage alongside pastor Saeed Abedini, had previously undertaken two hunger strikes to protest against being denied access to the medical treatment she requires for long-standing health issues. She was eventually allowed to temporarily leave prison to receive treatment, but each time forced to return before it could be completed.

The International Campaign for Human Rights in Iran notes that despite President Hassan Rouhani's pledges during his election campaign in 2013 that "All ethnicities, all religions, even religious minorities, must feel justice," the targeting of Christian converts has continued unabated under his administration.

According to Open Doors, at least 193 Christians were arrested or imprisoned for their faith there last year. The country is ranked 4th on the organization's World Watch List of countries where Christians face the most persecution, and has received the maximum score in the violence category.

Despite such ongoing persecution, the church in Iran continues to grow; in fact, the number of Christians in Iran grew 19.6 percent in 2015.

"The Islamic Republic of Iran is actually the place in the world where the Church is growing the fastest, something that would be pretty surprising to most Christians," Todd Nettleton from The Voice of the Martyrs said.

"So it is a country that has worked very hard to eliminate Christianity, and particularly to eliminate Muslim conversion to Christianity. But it's the place in the world where the Church is growing the fastest."